﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class User_FileDown : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Request.QueryString["filename"] == null)
        {
            Response.Write("<script>alert('错误跳转!')</script>");
            return;
        }
        System.IO.Stream iStream = null;
        // Buffer to read 10K bytes in chunk:
        byte[] buffer = new Byte[10000];
        // Length of the file:
        int length;
        // Total bytes to read.
        long dataToRead;
        // Identify the file to download including its path.
        string filepath = Server.MapPath("/") + ".\\ckfinder\\userfiles\\" + Request.QueryString["filename"];
        // Identify the file name.
        string filename = System.IO.Path.GetFileName(filepath);
        try
        {
            // Open the file.
            iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Open,
                        System.IO.FileAccess.Read, System.IO.FileShare.Read);
            // Total bytes to read.
            dataToRead = iStream.Length;
            Response.Clear();
            Response.ClearHeaders();
            Response.ClearContent();
            Response.ContentType = "text/plain"; // Set the file type
            Response.AddHeader("Content-Length", dataToRead.ToString());
            Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);
            // Read the bytes.
            while (dataToRead > 0)
            {
                // Verify that the client is connected.
                if (Response.IsClientConnected)
                {
                    // Read the data in buffer.
                    length = iStream.Read(buffer, 0, 10000);
                    // Write the data to the current output stream.
                    Response.OutputStream.Write(buffer, 0, length);
                    // Flush the data to the HTML output.
                    Response.Flush();
                    buffer = new Byte[10000];
                    dataToRead = dataToRead - length;
                }
                else
                {
                    // Prevent infinite loop if user disconnects
                    dataToRead = -1;
                }
            }
        }
        catch (Exception ex)
        {
            // Trap the error, if any.
            Response.Write("Error : " + ex.Message);
        }
        finally
        {
            if (iStream != null)
            {
                //Close the file.
                iStream.Close();
            }
            Response.End();
        }
    }
}
